1. Field of the Invention
The present invention relates to the process of designing integrated circuits. More specifically, the present invention relates to a method and an apparatus for inserting extra tracks in a library cell to facilitate migration of the cell to a different technology.
2. Related Art
As advances in deep-submicron fabrication technologies make it possible to achieve greater degrees of semiconductor integration, such integration makes the design of integrated-circuits (ICs) increasingly more challenging. By enabling multi-million-gate system-on-chip (SoC) designs, the latest generation of process technologies has widened the gap between manufacturing capabilities and designers' abilities to quickly design these complex devices. Reuse of existing layouts helps close this gap and enables companies to meet tight time-to-market objectives. However, conventional optical shrink techniques no longer work on existing silicon-proven layouts, because at deep-submicron level, different process design rules shrink by different factors.
Fortunately, a new generation of compaction-based electronic design automation (EDA) tools has emerged. These EDA tools can re-size and re-place millions of polygon edges described in an existing layout to conform to particular design rules. Consequently, they can better enable designers to migrate proven layouts to new technologies.
In a layout which is based on a standard library architecture, modern EDA tools are presently able to compact existing library cells to ensure that the target cell layout obtained after migration meets with the latest design rules. However, even with automatic compaction, there are still challenges in migrating certain types of library cells.
One such challenge is to migrate a cell containing tracks for metal wires. A cell typically includes one or more metal layers containing “tracks” where a metal wire can be placed for routing purposes. During migration, a cell ideally follows not only a set of process design rules, but also a set of corresponding template or architectural rules. For example, an existing metal wire ideally remains at the center within a track after additional tracks are added to a cell. Unfortunately, current compaction tools typically cannot guarantee meeting with such architectural rules.
Hence, what is needed is a method and an apparatus for inserting tracks into a library cell during migration of the cell to a different technology without the above-described problems.